Two-stage water heater



May' 1, 1945., E. R. KOPPEL 2,374,757

- 'TWO-STAGE WATER HEATER Filed Aug. 21, 1943 FIG. 1.

ATTORNEY.

Fatented May l, i945 nire err

raar

E? EE' 13 Claims.

This invention relates to a two-stage water heater.

The principal object of the invention is to provide the heater storage tank with a booster section for supplying relatively small quantities of veTY hot water.

Another object is to provide a heater with inter-connected heater storage chambers, one of which is adapted to store water at a, substantially higher temperature than the other.

Another object is to provide such a` heater in which the water inv4 the hotter chamber may be by-passed to the other chamber to,aid in heating the water therein.

Other objects and advantages will appear hereinafter.

The accompanying drawing illustrates an embodiment of the invention and the views thereof are as follows:

Figure l is a vertical central section through a heater; and

Fig. 2 is a transverse horizontal section taken on line 2-2 of Fig. 1.

The water heater comprises in general an up. right cylindrical water storage tank l with a gas burner 2 or other suitable heating means beneath the tank and a flue 3, preferably central of the tank for conducting the products of combustion/f ffrom the burner to a chimney.

The tank l may be of the type set forth in United States Patent No. 2,263,021 to Uecker, in which the cylindrical walls and head are of ordinary steel andare protected from corrosion by a lining of ceramic enamel or the like. The flue 3 is weld-edto the heads of the tank and should be constructed of suitableKnon-corrodible material or be suitably protected by a coating of such `material. v

A cold water inlet l is provided in the side wall near the bottom of the tank, and a hotnwater outlet 5 is similarly provided near the top of the tank. A thermostatic control valve B is secured to the side of the tank I at a suitable height to be responsive to the temperature .of the water in tank l at that height, and is connected to the gas supply pipe 'i for burner 2 to control `operation of the latter in a manner to maintain the Water in tank I at a given predetermined temperature.

In carrying out the invention an auxiliary storage chamber 8 is provided to receive heat directly from the ue 3 and to store water at a higher temperature than that in the. tank l. The chamber` B may be provided as a tank in the iiue, but preferably it surrounds the iiue and comprises a cylindrical wall 9 concentriowith the flue drawi and of substantially` smaller diameter than that of the shell of tank l. The upper and lower ends of cylinder S are closed by head plates l) which are secured to the flue 3 and serve to support the cylinder thereon. The wall 9 and heads i@ of chamber t are preferably constructed of heat insulating material.

A series of holes l l are provided in wall s near the bottom of chamber 8 for the inlet ci water from tank l to chamber 8. An outlet pipe l'i is connected to the upper end of chamber 8 for the purpose of drawing oil hot water therefrom. A. thermostatically controlled by-pass i3 is provided in the upper end of chamber il to discharge Water into tank i :when the water in chamber 8 exceeds a predetermined temperature.

It is contemplated that the valve it will be set to pass water when the water in chamber 8 reaches a temperature of about 170 to 180 F., whereas the thermostatically controlled valve 6 functions to maintain the water in tank t at a temperature between and 140 F.

1n operation the water in chamber t receives mstof the heat from the burner 2, and when it reaches the temperature for which valve le is set the valve opens and the water circulates by convection into tank l and downwardly therein, cooler water entering chamber 8 through holes ll to replace it. Additional heat is passed directly from burner 2 to tank l through the bottom of tank l. When the water in tank l at the level of the thermostat t' reaches the temperature for which the thermostat is set, valve t shuts ofi the supply of gas to burner 2. The thermostat tf again operates valve 6 to start the burner 2 when the water in tank l cools to a. predetermined lower setting ofthe thermostat.

When it is desired to draw oi very hot water, this is done through pipe l2 connecting with the upper end of chamber B. When it is desiredto draw off moderately hot water, this is done through outlet 5 at the upper end of tank l. The oi of water through outlet does not apprec bly lower the temperature of the Water in clrajnaiber, particularly since .thermostat E', will/start burner 2 operating after a comparatively small quantity of water has been drawn. Nor does the drawing off of water .through pipe l2 lower the temperature *ofl the water in vtank l, except as it may stop the by-passing of water through valve I3temporarily, and except for the fact that the incoming cold water, replacing the quantitydrawn from pipe I2, may trip thermostat '6'v and start burner 2 if lan appreciable quantity of water is drawn. i

vwithin the scope of the accompanying claims.

Iclaim: l. In a water heater, a water storage tank having a passage for hot gases therethrough to vheat the same, a secondary chamber in said tankand surrounding said passage to receive heat directly from the gases in said passage, a common source of water supply for said tank and said chamber, and a passage having a thermally controlled valve therein for the flow of heated water from said secondary chamber to said tank,

2. In a water heater, a water storage tank having a passage for hot gases therethrough to heat the same, a secondary chamber receiving heat directly from the gases in said passage, a common source of water supply for said tank and saidchamber, a thermally controlled passage for the beneath, a ue for conducting hot gases from said burner vertically upward through said'tank, a secondary chamber in direct contact with the hot gases in said ue for heating an enclosed quantity of water, means to admit water to said chamber from the lowerl end of said tank, means to admit water to the upper end of said tank from the upper end of said chamber, means to maintain said last named means closed when the water in said chamber is below a predetermined temperature, and means to withdraw heated waterfrom said tank and from said chamber selectively.

7. In a water storage heater, an upright sub'- stantially cylindrical tank with a heating burner beneath, a flue for conducting hot gases` from said burner vertically upward throughsaid tank, a secondary chamber in direct contact with the hot gases in saidue for heating an enclosed quantity of water, means to admit water to said chamber from the lower end of said tank, means to admit water to the upper end of said tank l from the upper end of said chamber, means to maintain said last named means closed when the water in said chamber is below a predetermined temperature, and thermostatic means for control'- ling said burner in response to the temperature flow of heated water from said secondary chamber to said tank, means to withdraw heated' Y flow of heated Water fromsaid secondary chamber to said tank, means to withdraw heated water from said tank and from said chamber independently, and means to regulate the 'supply of hotf gases to said passage in response to the temperature of the water in said tank, said last named means including a thermostat set at a lower temtrolled passage opens to maintain a. substantial Itemperature diierential between the water in said tank and the water in said chamber.'

5. In a water storage heater, an upright substantially cylindrical tank with a heating burner beneath, a ue for conducting h ot gases from said burner vertically upward through said. tank, a

of the water in said tank.

8. In a water storage heater,an upright substantially cylindrical tank with a heatingburner beneath, a flue for conducting hot gases from said burner vertically upward through said tank, a secondary chamber in direct contact with the hot gases in said ilue for heating an enclosed quantity of water, means to admit water to said chamber from the lower end of said tank, means to admit water to the upper end of said tank' from the .upper end of said chamber, means to maintain .said last named means closed when 40 the water in said chamber is below a predeter` 'mined temperature, thermostatic means for controlling said burner in response to the temperature of the water in said tank, and means to Withdraw heated water from said tank and'from said chamber, said last named thermostatic means being set to'maintain a s bstantial temperature than that at which said thermally con-v secondary chamber in direct contact with the hot ber from the lower end of said tank, means to admit water to the upper end'of said tank from perature differential between the ter in said tank and chamber.

9. In a water heater, an upright substantially cylindrical tank with a heating burner beneath, a flue extending upward. through said tank for conducting hot gases from said burner, a secondar'y heating chamber adjacent to said ue and having its bottom 4in direct communication with. the tank at the bottom ofthe latter and its top adapted to communicate with the'top of the tank to provide for circulation of waterbetween the two by convection, an outlet connection for heated water at the upper end of the tank, and a s epa- `rate outlet for heated Water directly from the ing chamber adjacent to said flue and being'in,

the upper end of said chamber, and means to maintain said last named means closed when the water in said chamberiisbelow a predetermined temperature. f

6. In a water storage heater, an upright sub-I direct communication with thetank at its bottom, an outlet connection for heated water 'at the upper end' of the tank,` asimilar outlet for'- heated water at the upper end of said chamber, and a thermostatically controlled valve in a passage between the upper ends of the chamber -and tank to eiect lconvection currents Ofheated stantially cylindrical tank with a heating burner water between the `chamber and tank when the water in said chamber has reached a prede-l termined temperature.

1l. In a water heater, an upright substantially cylindrical tank with a heating burner beneath, a flue extending axially upward through said tank for conducting hot gases from said burner, a secondary heating chamber surrounding said ue and being in direct communication with the tank at its bottom, an outlet connection for heated Water at the upper end of the tank, a similar outlet for heated water at the upper end of said chamber, a thermostatically controlled valve in a passage between the upper ends of the chamber.

burner, a secondary heating chamber adjacent to said ue for receiving heat directly therefrom and being in direct communication with the tank at its bottom, an outlet connection for heated water at the upper end of the tank, a separate outlet for -heated water at the upper end of said chamber, and a restricted passage for the ow of heated water from said chamber to said tank by convection. f

13. In a water heater, a plurality of chambers receiving heat from the same source and water from the same source, one of said chambers being disposed to receive more heat from said source than the other, intercommunicating means between said chambers for establishing a convectional ow of heated water from said more highly heated chamber to another when the water in said i'lrst chamber exceeds a given temperature, and means for preventing said convectional flow of water unless the water in said more highly heated chamber is at a temperature substantially above the temperature of the water in said other ERNST R. KOPPEL. 

